This invention relates to print media, and more particularly to techniques for marking clear or transparent film media with indicia readable by an inkjet printer, copier, fax machine, large format printer or other printing mechanism.
Inkjet printing systems are in widespread use today. Ink jet printers print dots by ejecting very small drops of ink onto the print medium, and typically include a movable carriage that supports one or more printheads each having ink ejecting nozzles. The carriage traverses over the surface of the print medium, and the nozzles are controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to the pattern of pixels of the image being printed. Color ink jet printers commonly employ a plurality of printheads, for example four, mounted in the print carriage to produce different colors. Each printhead contains ink of a different color, with the commonly used colors being cyan, magenta, yellow, and black. Printing devices may have several features or other options, such as print speed, driver selection, dry time and print mode to provide the best quality for a particular media.
Printing devices, such as inkjet printers, use printing composition (e.g.,ink or toner) to print text, graphics, images, etc. onto print media. The print media may be of any of a variety of different types, sizes, side-specific coatings, etc. For example, the print media may include paper, transparencies, envelopes, photographic print stock, cloth, plastic, vinyl, special material, etc. Each of these types of print media have various chemical and physical characteristics that ideally should be accounted for during printing; otherwise less than optimal printed products may occur. Additional characteristics may also affect print quality, including print medium size, print medium orientation, and print medium sideness.
One way in which a printing device can be configured to a particular print medium is to have a user make manual adjustments or make program inputs to the printing device based upon these characteristics and factors. One problem with this approach is that it requires user intervention which is undesirable. Another problem with this approach is that it requires a user to correctly identify various characteristics of a particular print medium which the user may not know. A further problem with this approach is that a user may choose not to manually configure the printing device or may configure the printing device incorrectly so that optimal printing still does not occur in spite of user intervention. This can be time-consuming and expensive depending on when the configuration error is detected and the cost of the particular print medium.
It would therefore be an advantage to be able to automatically read media characteristic information automatically and without requiring user input, by having the media communicate directly to the printing device.
Inkjet printers can support printing images on a variety of print media types, including plain paper, coated paper, clear film media, as well as others. There are several known methods for marking paper media with machine readable indicia, including visible indicia and indicia not visible to the human eye under normal ambient lighting conditions.
It is known to place one indicia on the media. This indicia is usually placed on the front of the media. The media has to be loaded with the correct face up. If the media is loaded with the correct side up, but the wrong edge forward, the printer would read the indicia across the entire page and invert the image internally. There are two disadvantages to this system. First, it requires the media to be loaded with the correct side up. Second, it requires an expensive reading equipment to read the indicia across the entire page. To avoid the problem of requiring the media to be loaded with the correct face up, a second reading device may be used to read the indicia off the bottom face of the media; however this increases the cost of the sensor.
If only one indicia mark is placed on a sheet of media, then the sheet must be either loaded into the printer in the correct orientation or the printer must be able to read the indicia in any orientation. It is desirable to allow the user to load a sheet of media in any orientation, so the first option is not acceptable. For a printer to have the capability to read a mark in any orientation requires a sophisticated reading device in the printer.
A technique is described for marking media with indicia in such a way as the media may be loaded into the printer in any orientation. These indicia marks are read by a printer for the purpose of identifying the media, determining the orientation of the media, and providing additional information about the media. The indicia encodes the necessary information for the printer to identify the media as well as additional information about the media that may be useful for the printer. In a typical embodiment, the indicia will be invisible to the human eye but machine readable. On sheets of media, indicia are placed in the margin of the media in eight corners of the page, four on the front and four on the back. The indicia are placed and orientated such that the indicia are in the same relative position and orientation to the printer regardless of the orientation in which the media is loaded into the printer.
In accordance with an aspect of this invention, a simple, inexpensive reading device may be used in the printer, and need only be capable of reading indicia in one position on a sheet of media. With the mark replicated in all eight corners, the sensor will correctly read the mark regardless of the orientation of the media.
It is also desirable to know the orientation of the media loaded into the printer. By placing a slightly different indicia in each corner of the media, the printer can determine the orientation based on the information encoded in the indicia.